Lubricating oil additives



Patented May 18, 1954 LUBRICATING OIL ADDITIVES Thomas Stanford Tutwile H. Bartlett, Westfield, N. J assignors to Standard Oil Development Company, a corporation of Delaware r, Elizabeth, and Jeffrey No Drawing. Application December 29, 1948, Serial No. 68,086

1 7 Claims.

The present invention relates to copolymers of unsaturated dibasic acid esters and their derivatives with acrylic esters and related compounds. The present invention further relates to the use of polymeric materials of this general type as additives for lubricating oils, hydraulic oils and analogous compositions and to the formulation of oil compositions and the like as new products of manufacture. The invention further relates to processes for producing products of the character referred to above.

It has now been found and is the subject matter of'the invention, that alpha-methylene dicarboxylic acid esters readily copolymerize with alpha, beta unsaturated monocarboxylic compounds to yield oil soluble products which are particularly valuable as lubricating oil additives such as viscosity index improvers, pour depressants, and the like.

It is well known in the prior art that mineral base lubricating oils and, particularly, lubricating oils such as those used in the crank cases of automotive engines, have serious limitations with respect to viscosity-temperature relationships and pour point unless they are prepared from carefully selected materials or are modified to improve their viscosity and/ or their pour characteristics. The present invention has, as a major object, the production of improved additive materials for oils which are suitable for improving viscosity index and lowering the pour point.

While reference is made above to lubricants forautomotive crank cases, it will be understood that the invention has application to other type lubricants and is applicable generally to hydrocarbonioil fractions such as hydraulic oils and in some instances to synthetic oils which are employed similarly to naturally occurring mineral oils.

A further object of this invention is to produce a polymeric material which is useful as a thickener for oils and which may be used in various hydrocarbon base stocks derived from various crude oils, such as paraiiinic, naphthenic, asphaltic or mixed base. A still further object is to prepare a material which does not lose its properties of depressing the pour points of oils upon repeated cycles of temperature change above and below the normal pour points. Many materials which are effective pour point depressors in lubricating oils, for example, become unsatisfactory after being subjected to a large number of temperature changes. This property which is commonly referred to as pour instability is highly objectionable and an important object of this invention is to prepare materials, and lubricating oils containing such materials which are free from pour instability.

As an important aspect of the present invention, it has been discovered that excellent polymeric lubricating oil additives may be produced by copolymerizing alpha methylene unsaturated dicarboxylic acid esters with alpha, beta-unsaturated monocarboxylic compounds having the formula R It CH2=COOOR COOR where 91:0, 1, 2 or 3 or mixtures thereof, and R and R are the same or different alkyl, alicyclic, aralkyl or alphyl group. Examples of these esters are alpha-methylene malonic esters,

itaconic esters, alpha-methylene glutaric esters and alpha-methylene adipic esters.

It is important that the copolymers of the type described herein contain sufficient long hydrocarbon side chains, containing from about 6 to about 24 carbon atoms, to impart oil solubility to the copolymer. These long chains may be present in the alpha-methylene dicarboxylic esters or they may be present in the alpha, beta unsaturated compound. The presence ofthese relatively long chains also gives desirable properties to the copolymer. For the production ofpour depressants, it is essential that there be side chains containing 10 or more carbon atoms.

These chains may be supplied by alcohols used,

to prepare the alpha-methylene dicarboxylic estersor the alpha, beta unsaturated monocarboxylic compounds. One commercially available alcohol suitable for the pr paration of the esters is obtained from the hydrogenation of coconut oil. Such a product is sold under the trade name Lorol and is a mixture of saturated straight chain primary alcohols ranging from 10 to 18 carbon atoms and having a major proportion of lauryl alcohol which has 12 carbon atoms. Other related products are made by separating this material, which may be considered as a crude mixture, into several different fractions having a relatively higher proportion of the higher, lower, or medium constituent thereof. The composition of Lorol per se and related products, Lorol B and Lorol R, is approximately as follows:

Composition of mixtures of commercial alcohols Lorol Lorol B Lorol R 010 -Pereent- 4 3 1 do. 55. 5 46 85 do 22. 5 24 13 do l4 l 1 "do" 4 17 Average number of carbon atoms 12. 8 l3. l2. 2

and alphyl alcohols such as alkylated phenols,

cresols, etc. can be employed. The above-mentioned alcohols may contain functional groups such as halogen, -NH2, -CN, -NO2, -OR., -O-(CH2)n-OR, eta, provided they do not interfere with copolymerization or render the copolymer insoluble. Whereas, straight chain and slightly branched aliphatic primary alcohols give excellent results and are therefore preferred, the other types of alcohols and their derivatives mentioned above can be employed for preparing the ester monomers which are copolymerized according to the invention. It will be understood that mixtures of alcohols of the same type or of different types can be employed. In the case of esters prepared from the alpha-methylene dicarboxylic acid, mixed esters such as methyl decyl itaconate can be copolymerized with the alpha, beta-unsaturated monocarboxylic compound with good results.

Half esters of alpha-methylene dicarboxylic acids may also be used in the preparation of copolymers. The resulting products contain free oarboxyl groups which may be used as such. or which may be converted to ammonium, amine, or metallic salts for special purposes.

The conditions for copolymerization in the present invention may involve either bulk or emulsion technique. In bulk copolymerization diluents may be used in order to control reaction rate or copolymer molecular weight, such as hydrocarbons, esters, ethers, halides, and the like, although this is not always necessary. Catalysts such as benzoyl peroxide, t-butyl hydro-' peroxide, cumene hydroperoxide and other peroxides may be used although other catalytic sys- 4 tems such as BF3, AlCls, voltollzation, activated clays, and the like may readily be used.

Various conditions of copolymcrization may be used in this invention involving the presence or absence of diluents at temperatures ranging from C. to 150 C. for periods ranging from 5 minutes to 100 hours. When employing peroxide catalysts, for example from 0.1 to 10% preferably about 1.0% by weight based on the monomers, and temperatures in the range from about 60 to 100 C., the reaction will generally be substantially complete in 5-20 hours depending on the particular monomers being copolymerized.

The average molecular weight of the finished polymeric material should not be less than 1,000 or more than 50,000. The preferred range is about 5,000 to 20,000, a molecular weight of 7,000 to 17,000 being especially preferred.

The copolymers which are produced according to this invention not only are suitable pour depressants and viscosity index improvers but also are rust inhibitors, detergents, and generally improve the condition of the engines in which they are used. These copolymers may also be used in compounding greases, waxes, and the like and may also be used in conjunction with other additive materials such as rust inhibitors, detergents, extreme pressure agents, dyes, other V. I. improvers, other pour depressants, and the like.

The invention will better b understood from the specific examples described hereinafter which are illustrative only and are not to be construed as limiting the scope of the applicants invention.

EXAMPLE I To 1900 g. (12 m.) of n-decanol and 860 g. (6.6 m.) of itaconic acid contained in a 5 liter, 3 necked flask equipped with a stirrer, water trap and reflux condenser were added 500 g. of 54 naphtha and 5 g. of sulfosalicylic acid. This mixture was heated for 23 hours during which time 215 g. (99% theory) of water were collected. The reaction mixture was washed three times with equal volumes of 5% NaHCOx solution to remove the excess itaconic acid, and then with water until the wash was neutral to litmus. The washed ester was stripped with nitrogen on a steam table to completely remove the 54 naphtha and at the completion of this step was ill-- tered through diatomaceous earth.

To 160 parts of decyl itaconate, prepared as described above, were added so parts of freshly distilled methyl acrylate and parts of a white oil, having 43 SUS viscosity at 210 11"., in a 500 cc. stirring flask provided with a reflux condenser and contained in a heating bath. The mixture was then heated at 60 to 70 C. in a nitrogen atmosphere for 7 hours, adding 1 part of benzoyl peroxide at the start of the heating period and 1 part of benzoyl peroxide after heating the mixture one hour. The copolymer thus obtained was blended to 20% concentration in a mineral oil such as a lubricating oil having a 43-44 SUS viscosity at 210 F. and this oil concentrate was employed directly as a V. I. improver.

EXAMPLE II To 160 parts of decyl itaconate, prepared as described in Example I, were added parts of freshly distilled methyl methacrylate and 35 g. of the above identified white oil, in a 500 cc. stirring flask provided with a reflux condenser and contained in a heating bath. The mixture was then heated at to C. in a nitrogen atmosphere for 7 hours, adding 1 g. of henaoyl peroxide at the start of the heating period and 1 g. of benzoyl peroxide after heating the mixture one hour. The copolyiner thus obtained was blended to 20% concentration in a mineral oil having 13-44 viscosity at 210 F. this oil concentrate was employed directly a V. 31. improver.

6 sentially of a major proportion of a waxy mineral lubricating oil and about 0.1% to 3.6% by weight of a copolymer of a C6 to Car alkyl ester of itaconic acid and a compound having the formula R capo-occurs wherein R represents a radical selected from the class consisting of H, and CE2.

V. 1. Improving Properties of Copolymers Viscosity BUS Baso Oil having 115 V. l. and i5 BUS Viscosity at 210 F.+ at 210 F.. 20% ggfig l i g 1.2 Wt. Percent 2.4 Wt. Percent 3.0 Wt. Percent Copolsgmer Reference OH Polymer Polymer Polymer Num er halving adVv I.

of 12 an Viscosity, Viscosity, Viscosity coslty 10" 1 v I 210 F. v.1 no F v I SUS at 210 F. SUS SUE Example I 5:50 52. 2 143 60. 4 148 71. 7 152 Example II 356 49. 140 53. 7 151 59. 155

EXAMPLE II).

Acne liter necked fiasis equipped with a stirrer, thermometer, reflux condenser Was charged with 120 g. of the above identified White oil, 14% g. of Lorol B itaconate, prepared in accordance with copending application, Serial No. 37,091, by J. H. Bartlett, now abandoned, and heated in an oil oath to C. The air Was replaced with nitrogen after which 36 g. of freshly distilled methyl acrylate was added through the condenser. To this mixture was added a total of 2.15 g. benzoyl peroxide during 3 ho rs in 3 portions. The copolymerization was continued at 70 C. for 22 hours after which the copolymer was diluted to a blend in a lubricating oil of SAE 10 Viscosity of the 20% blend was 1674 Saybolt seconds at 2 0 F.

EXAMPLE IV A copolymer was prepared from 144. g, Lorol B itaconate, prepared in accordance with the procedure in Serial No. 37,091, 36 gm. methyl methacrylate in 120 g. of a white oil having 43 SUS viscosity at 210 using 2.16 g. benzoyl peroxide under the same conditions as used in Example III except that the copolymerization was. carried out for 5 hours. A 20% blend of the copolymer in the lubricating oil had a viscosity at 210 1 of 29"! Sayloolt seconds.

The copolymerie products of Examples 111 to IV wer 1i in two reference oils, oil A being a Mid-Continent acid treated neutral SAE grade 10; oil 3 being a Mid-Continent acid-treated neutral blended with Pennsylvania tight stock, SAE grade 36. The ASTM pour points of the blends are shown in the following table.

Pour Deprcssant Properties of C'opoZg mers AS'lM Pour Point of Blends in Referonce Oils Percent Concentration of Active Ingredient Copolymer Non Example IV What is claimed is: 1. A lubricating oil composition consisting cslubricating oil amount of a copolyrner of .0 mo} of Lorol B itaconate 0.1 to 2.0 mole of methyl acrylate.

4. A. lubricating oil. composition consisting essent 11 of a or proportion of a Waxy mineral lubricating oil and a small but pour depressing a .ount of a copolyiner or" 1.0 11201 of Lorol B itaoonate and 0.1 to mole of methyl methacrylate.

5. A lubr'cating oil composition consisting essentially of a major portion of a mineral oil base stock an improving amount of a copolymer of 1.0 mol of decyl itaconate 0.1 to 2.0 niols of methyl methacrylate.

6. Aiuhricating oil composition consisting essentially of a, major proportion of a mineral lubricating oil and a viscosity index improving amount of copolyrner oi decyi itaconate and a compound, having the formula If. CE2=C-OOOCH3 wherein it is selected from the class consisting of hydrogen and a methyl group.

A lubricating oil. composition consisting essentially of a major proportion of a Waxy mineral lubricating oil a small but pour point depressing amount of a copolymer of Lorol B itaconate and a compound having the formula t CH2=O-OOOOH3 wherein it is selected from the group consisting of hydrogen and a methyl group.

References fitted in the file of this patent UNITE? STATES PATENTS number Name Date 2,149,852? Mikeska Mar. 7, 1939 2,220,355 slagh Nov. 5, 1940 2,279,881 DAlelio Apr. 14, 1942 2,279,883 DAlelio Apr. 14, 1942 2,327,705 Frolich Aug. 24, 1943 2,38%,595 Blair Sept. 11, 1945 2,422,881 Blair June 24, 1947 

1. A LUBRICATING OIL COMPOSITION CONSISTING ESSENTIALLY OF A MAJOR PROPORTION OF A WAXY MINERAL LUBRICATING OIL AND ABOUT 0.1% TO 3.6% BY WEIGHT OF A COPOLYMER OF A C6 TO C24 ALKYL ESTER OF ITACONIC ACID AND A COMPOUND HAVING THE FORMULA 